An experimental investigation on the integral waterproofing capacity of polypropylene fiber concrete with fly ash and slag powder

Abstract

The influence of polypropylene fiber (PF) on the waterproofing performance and chloride resistance of high performance concrete (HPC) made with fly ash and slag powder is comprehensively investigated from macro and micro perspectives via a series of experimental tests, including (i) slump and mechanical tests to measure the workability, (ii) capillary water adsorption tests to investigate the waterproofing capacity, (iii) chloride penetration tests to investigate the chloride resistance and (iv) mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM) tests to observe the pore size distribution and the microstructure. Test results reveal that the addition of PF to HPC improves its waterproofing capacity and chloride resistance while having little effect on the workability. The waterproofing capacity and chloride resistance improve as the volume fraction of PF increases in the range of 0–1.35 kg/m3. Based on the results of MIP and SEM tests, the mechanism of the effects of PF on waterproofing and chloride resistance is also analyzed. Adding PF to the concrete mixture results in a decrease of the pore size, a decrease of the porosity, an enhancement of bonding between C-S-H and Ca(OH)2, and a much denser interfacial transition zone. All these microstructure changes contribute to the increase of the waterproofing performance and chloride resistance of PF-reinforced HPC made with fly ash and slag powder.